Worcester Bosch GREENSTAR 30SI water pressure problems

Hi All,
Can anyone help. The water prssure gauge on my Greenstar 30Si continually goes to 0 prressure whenever the central heating stops. I've had the RCI installer return 2 times and he doesn't seem to be able to solve the problem. I am on normal water supply - Severn Trent in Birmingham. One time the Installer bled the system and introduced a sealant - that has not worked. He thought one of the rad may have a leak - they were all sound. Anyway if that was the case surely the sytem would run dry during operation.

Anyone got any clues about what it could be - is there an issue inside the boiler mechansim and valve which could be causing the issue.

If you put pressure in the boiler to say 1bar and you put the heating on is the gauge going unto 3bar? You should then notice the copper pipe which is connecterd to the safety valve and goes outside will probably be dripping if so then the expansion vessel will either need recharging or replacing!

Thanks Barry - I tried what you said putting the pressure to 1bar - and sure enough when the heating fired up it moved up to 3 Bar and went above that, then started to make various noises. Outside the copper exit pipe was dripping.
If I get an engineer iand ask them to replace it - whats the correct terminology to get them to do it - and what would be your estimation of the cost?

Take the little air cap off the expansion vessel and press the little pin in, if there is water in there it is definately split. If you get nothing, then it may just need repressurising.

Click to expand...

As above the vessel is accessed at the back of the boiler and over the top near the flue. The pin is a schrider valve which is the same as the one on a bike inner tube.
See the FAQs at the top of the plumbing and heating, ChrisR explains it very well.
As for cost it would depend if it needs recharging or replacing!

Thanks to both above - very helpful. If the vessel is faulty could this be a major job for the engineer. Just trying to get an idea on costs. Because I would prefer to get a qualified heating /plumbing engineer in to do the work. Any suggestions for around the Birmingham area?

i have a powermax 155x 2002 and recently the water pressure dropped to 0 after using hot water..if i re pressurise up to 1.5-2 it just repeats and the red light lockout comes on.
ive had 3 peeps out and not the solution yet..could be a leak,or re pressurise or aav or prv but im a total novice and would be grateful for any help or if anyone is near cardiff am happy to offer the work out.
thanks

I have exactly the same problem with the same boiler. I'm fed up of filling it up every morning before the heating kicks in. Did anyone manage to find a solution, or figure out if it was the expansion valve?